1. Field of the Invention
The present invention relates to a transmission for an auxiliary device for transmitting a driving force of an engine to an auxiliary device of an automotive vehicle.
2. Description of the Related Art
A transmission for an auxiliary device in accordance with the related art comprises a planetary-gear-typed speed increasing mechanism, a multiple disc clutch, a hydraulic actuator for pressing and engaging the multiple disc clutch, an oil pump for applying an oil pressure to the hydraulic actuator, a pressure adjusting valve for adjusting the oil pressure applied to the hydraulic actuator from the oil pump, a controller for adjusting an opening degree of the pressure adjusting valve so as to adjust a pressing force of the hydraulic actuator and the like, and serves to transmit the driving force of the engine to a supercharger.
A pinion carrier of the speed increasing mechanism is connected to the engine, a sun gear is connected to the supercharger and the multiple disc clutch is disposed between an internal gear and a casing of the transmission for an auxiliary device.
When the multiple disc clutch is engaged, the driving force of the engine is increased by the speed increasing mechanism so as to drive the supercharger and the driven supercharger supercharges the engine by pressurized intake air.
Generally, when the engine is in an idling state or in a low speed rotation, a rotation speed is greatly varied. As is well known, the variation of the rotation speed is particularly greater in a diesel engine than in a gasoline engine.
If the variation of the rotation speed is generated in the engine, a rattling noise of gear is generated in a timing gear set of the speed increasing mechanism or the supercharger due to a variation of a torque so that a sliding is generated in the multiple disc clutch or a press fitting portion of a gear.
Then, in the transmission for an auxiliary device, the controller monitors a torque applied to the internal gear through a torque sensor, and loosens a pressing force of the hydraulic actuator so as to slide the multiple disc clutch when a great torque is applied. Accordingly, it decreases a range of the variation of the torque by loosing a peak of the torque.
However, since the above transmission for an auxiliary device decreases the variation of the torque by sliding the multiple disc clutch, a clutch disc of the multiple disc clutch is greatly abraded by a frequent sliding so that a durability thereof is greatly lowered.
Further, in order to adjust the pressing force of the hydraulic actuator, it is necessary to provide various kinds of sensors and a controller for calculating so that a structure thereof becomes complicated and a cost therefor or becomes expensive.
Still further, since the pressing force control of the hydraulic actuator is performed by an oil pressure, a control response of the pressing force is bad so that the variation of the torque is insufficiently reduce.
Furthermore, in a structure using a viscous fluid clutch or a magnetic fluid clutch, since the torque is transmitted through a fluid in both cases, a transmission response of the driving force is bad. When a fluid resistance is set great in order to improve the response, a reduction effect of the torque variation is deteriorated.